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Appl. Phys. Lett. 121, 103502 (2022); https://doi.org/10.1063/5.0109020 121, 103502
© 2022 Author(s).
A Weyl semimetal WTe2/GaAs 2D/3D
Schottky diode with high rectification ratio
and unique photocurrent behavior
Cite as: Appl. Phys. Lett. 121, 103502 (2022); https://doi.org/10.1063/5.0109020
Submitted: 11 July 2022 • Accepted: 22 August 2022 • Published Online: 09 September 2022
Jina Wang, Hanyu Wang, Quan Chen, et al.
A Weyl semimetal WTe
2
/GaAs 2D/3D Schottky
diode with high rectification ratio and unique
photocurrent behavior
Cite as: Appl. Phys. Lett. 121, 103502 (2022); doi: 10.1063/5.0109020
Submitted: 11 July 2022 .Accepted: 22 August 2022 .
Published Online: 9 September 2022
Jina Wang,
1
Hanyu Wang,
1
Quan Chen,
1,2
Ligan Qi,
1
Zhaoqiang Zheng,
3
Nengjie Huo,
1,2,4
Wei Gao,
1,2,4,a)
Xiaozhou Wang,
1,2,4,a)
and Jingbo Li
1,2,4
AFFILIATIONS
1
Institute of Semiconductors, South China Normal University, Guangzhou 510631, People’s Republic of China
2
School of Semiconductor Science and Technology, South China Normal University, Foshan 528225, People’s Republic of China
3
School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, People’s Republic of China
4
Guangdong Provincial Key Laboratory of Chip and Integration Technology, Guangzhou 510631, People’s Republic of China
a)
Authors to whom correspondence should be addressed: gaowei317040@m.scnu.edu.cn and wxzanu@outlook.com
ABSTRACT
Since the discovery of Dirac semimetal graphene, two-dimensional (2D) Weyl semimetals (WSMs) have been widely used in low-energy pho-
ton detection, polarization imaging, and other systems due to their rich physical characteristics, such as unique nonlinear optical structure,
topological nontrivial electronic structure, thickness-tunable bandgap, high electric conductivity, and so on. However, it is difficult to detect
the photocurrent signal at room temperature because of its large intrinsic background current. Fortunately, the fabrication of a van der
Waals (vdW) heterojunction based on WSM can effectively suppress the background current, greatly extend the detection range, improve
the light absorption efficiency, and increase the response speed. Herein, the 2D type-II WSM 1T0-WTe
2
/bulk GaAs vdW vertical Schottky
diode is investigated. Benefiting from the lateral built-in electric field of 260 meV and zero-bandgap structure of 52 nm 1T0-WTe
2
, it delivers
a rectifying ratio over 10
3
and can respond to the wavelength range of 400–1100 nm. Particularly, when the light power density is 0.02 mW/
cm
2
, the maximum photoresponsivity (R) and specific detectivity (D
) under 808 nm are 298 mA/W and 1.70 10
12
Jones, respectively.
Meanwhile, the I
light
/I
dark
ratio and response time are 10
3
and 520/540 ls, respectively. Moreover, an abnormal negative response behavior
can be observed with thin WTe
2
(11 nm) under 1064 nm illumination because of the open surface bandgap. It is suggested that such 2D
WTe
2
/GaAs mixed-dimensional vdW structure can be extended to other WSM/3D semiconductor junctions and used in fast response and
wide broadband spectrum photodetectors’ arrays.
Published under an exclusive license by AIP Publishing. https://doi.org/10.1063/5.0109020
In general, graphene with gapless surface states is verified to be
a representative sample of type-I Weyl semimetals (WSM). Its band
inversion can lead to anisotropic massless Weyl points in low-energy
excitations. Due to the strong surface plasmon polarization, gra-
phene can increase the bandwidth of absorption in the far infrared
and THz absorbers.
1–3
Moreover, among 2D transition metal dichal-
cogenides (TMDs), a new type of WSM called type-II WSM with
broken time-reversal symmetry possesses a strong tilted Weyl cone.
Therefore, the number of electron and hole pockets near the Weyl
cone creates an open Fermi surface composed of a nearly flatband.
4
WSM also occurs in epsilon-near-zero (ENZ) materials, showing
superconductivity, negative magnetoresistance, chiral anomaly, light
tunneling, vanishing group velocity, and perfect absorption.
5–9
For instance, 2D WSM WTe
2
with no centrosymmetric crystal struc-
ture possesses nondegenerate Dirac linear energy dispersion of con-
duction and valence bands, which intersect at pairs of Weyl nodes
and conducting Fermi arc states on its surface. Its gapless structure
can prevent backscattering during the transport, enabling supercon-
ductivity, quantum oscillations under pressure, doping, or electro-
static gating.
10–12
In the optical response, WSM WTe
2
was reported
to show robust edge photocurrent,
13
polarized photocurrent,
14
tera-
hertz response, nonlinear optical response,
15
and negative photores-
ponse behavior.
16
However, the photoresponsivity is only several
lA/W because of the displacement current. When the bias is applied,
the intrinsic dark current is very large, and the noise interference is
serious. Therefore, the application in low-power consumption
Appl. Phys. Lett. 121, 103502 (2022); doi: 10.1063/5.0109020 121, 103502-1
Published under an exclusive license by AIP Publishing
Applied Physics Letters ARTICLE scitation.org/journal/apl
devices and a high-performance broadband photodetector based on
WSM WTe
2
is limited.
Fortunately, since there are no surface dangling-bonds on the 2D
layered materials,
17,18
the lattice mismatch constraint will not need to
be considered,
19
and 2D WSM WTe
2
can be considered to build 1D/
2D, 2D/2D, and 2D/3D van der Waals (vdW) architectures for photo-
diodes and phototransistors. They can not only show the excellent
properties of individual materials but also achieve unique photores-
ponse performance such as photovoltaic, photothermoelectric, and
photogating effects.
20–22
For example, Liu et al. reported an all-
semimetal heterojunction based on graphene/WTe
2
. A high photores-
ponsivity of 8.7 A/W under 650 nm illumination at V
ds
¼0.5 V can be
achieved.
23
Moreover, Zeng et al. investigated a WTe
2
/MoTe
2
semi
metal/semiconductor heterojunction with the regulation of gate voltage
(V
g
), and the self-driven photoresponsivity is 220 mA/W at the V
g
of
40 V under 532 nm irradiation.
24
As we know, GaAs has a direct bandgap of 1.42 eV, which ena-
bles it to possess strong light–matter interaction, such as fast response
time and moderate R from the visible to near infrared light region.
However, the cutoff wavelength is limited to around 900 nm, which
cannot meet the application in optical communication.
25,26
Zeng et al.
fabricated a semi metallic PtSe
2
/GaAs Schottky photodetector. Under
808 nm illumination, the maximum R and D
are 262 m A/W an d 10
12
Jones, respectively, but the rectification ratio is only 120 and the
threshold voltage (V
th
) is close to 1 V.
27
Benefiting from its gapless lin-
ear dispersion and the enhanced nonlinear optical effect of WSM
WTe
2
, it is believed that 2D WSM WTe
2
combined with GaAs
substrate can improve the rectification behavior in the dark and
enhance the photovoltaic performance at the near infrared region.
In this Letter, a 52 nm 1T0-WTe
2
/3D GaAs vdW vertical
Schottky diode was fabricated. As a result, a large rectification ratio
over 10
3
can be achieved, ascribing to the large Schottky barrier height
of 570 meV. I t can detect the wavelength range of 400–1100 nm, and
the dark current is 20 pA at zero bias. Under 808 nm irradiation,
benefiting from the effective built-in electric field of 260 meV across
the high-quality interface, the maximum R, D
, and photoelectrical
conversion efficiency (PCE) are 298 mA/W, 1.70 10
12
Jones, and
3.52%, respectively. An abnormal negative response behavior can be
seen in the device based on thin WTe
2
(11 nm) under 1064 nm illumi-
nation because of the surface bandgap open. The large rectifying ratio
and excellent self-driven near-infrared response behavior are expected
to be used in low-power multifunctional optoelectronic devices in
future.
The device fabrication and the schematic illustration for the fab-
rication process of the WTe
2
/GaAs photodetector are given in the
Experimental section and Fig. S1 in the supplementary material,
respectively. Figure 1(a) shows the 3D diagram of a WSM WTe
2
/N-
GaAs Schottky photodetector. The optical image is shown in Fig. S2.
Furthermore, Raman spectrum was used to confirm the phonon vibra-
tion and interlayer coupling effect for bare WTe
2
and its heterojunc-
tion. As shown in Fig. 1(b),theRamanpeaksof1T
0-WTe
2
are located
at 77, 108, 130, 160, and 208 cm
1
on the SiO
2
and GaAs substrates,
all of which are consistent with the previous report.
28,29
The decrease
in peak intensities (called “Raman soften”) on GaAs also indicates the
FIG. 1. (a) Schematic of the as-fabricated WTe
2
/GaAs vertical Schottky heterojunction photodiodes. (b) Raman spectra of the WTe
2
on the SiO
2
and GaAs. (c) The height pro-
file of the device along the pink line. Inset shows corresponding Atomic Force Microscopy (AFM) image. (d) Surface potential difference profile of the WTe
2
/GaAs heterojunc-
tion along the blue line. Inset shows corresponding Kelvin Probe Force Microscopy (KPFM) image.
Applied Physics Letters ARTICLE scitation.org/journal/apl
Appl. Phys. Lett. 121, 103502 (2022); doi: 10.1063/5.0109020 121, 103502-2
Published under an exclusive license by AIP Publishing
enhancement of interlayer coupling between WTe
2
and GaAs. As
shown in Fig. 1(c), a height profile along the marked line in the
inset diagram is given, and the thickness of WTe
2
is approximately
52 nm with a clean and smooth surface. Simultaneously, Kelvin Probe
Force Microscopy (KPFM) was used to measure the surface potential
difference (SPD) between WTe
2
/GaAs and infer the Fermi level of
individual materials and the built-in potential difference. Figure 1(d)
shows the SPD mapping and the extracted potential profile.
Accordingly, the SPD of WTe
2
flakes or GaAs can be calculated as
follows:
30
eSPDWTe2¼Wtip WWTe2;(1)
eSPDGaAs ¼Wtip WGaAs;(2)
where eis the electron charge and Wtip,WWTe2,andWGaAs are the
work functions of KPFM tip, WTe
2
,andGaAs,respectively.
Therefore, the work function difference between WTe
2
and GaAs,
namely, the Fermi energy level difference (DEf), can be obtained by
calculating the following equation:
30
DEf¼WWTe2WGaAs ¼eSPDGaAs eSPDWTe2:(3)
The DEfbetween WTe
2
/GaAs is measured to be about 260 meV, indi-
cating that the WGaAs is higher than WWTe2, and the lateral depletion
width is 5.08 lm.
The I
ds
–V
ds
characteristics of the WTe
2
/GaAs heterojunction
device were tested under dark condition, as shown in Fig. 2(a).
Obviously, the device shows unidirectional conductivity with typical
non-linear characteristics. The rectification ratio was calculated to be
1.8 10
3
at V
ds
¼0.6/0.6 V. To prove that this rectification behavior
is formed by the WTe
2
/GaAs interfacial depletion region, we also
tested the I
ds
–V
ds
characteristics of Ag/GaAs/Ag and Au/WTe
2
/Au
and found that they formed Ohmic contact, as shown in Figs. S3(a)
and S3(b).
27
Therefore, the rectification property is judged to be
derived from the WTe
2
/GaAs interface. In addition, the V
th
is deduced
to be as small as 0.3 V. As shown in Fig. S4, the Schottky barrier height
(UB) can be extracted by fitting the I
ds
–V
ds
curve at the forward
region. The corresponding UBis as large as 0.57eV by using the diode
equation based on the thermionic-emission theory. Meanwhile, the
ideality factor (n) of 1.09 close to 1 suggests few recombination pro-
cesses inside the space-charge region or barrier layer between 1T0-
WTe
2
and GaAs. The forward current is dominated by the
Schockley–Read–Hall recombination process. As shown in Fig. 2(b),
the rectifying ratio of WTe
2
/GaAs vdW is superior to that of other
WTe
2
-based heterojunction and mixed-dimensional GaAs based het-
erojunctions. Moreover, the wavelengths of 405, 635, 808, and
1064nm laser are selected to illuminate the device. As shown in
Fig. 2(c), the illumination current tends to almost saturate at the V
ds
range from 0 to 0.6 V because of the large built-in electric field across
the interface, with negative short-circuit current (I
sc
) of 0.31, 0.88,
1.71, and 1.05 nA and positive open-circuit voltage (V
oc
) of 4, 112,
155, and 158 mV at 405 (0.23), 635 (0.19), 808 (0.23), and 1064 nm
(0.19 mW/cm
2
), respectively. Obviously, the response range of the
photodiode is wider than the bare GaAs photodetector owing to the
light absorption of WTe
2
, and the optimal wavelength is 808 nm.
Figure 2(d) displays the stable and reproducibility time-resolved pho-
toresponse to various light wavelengths.
FIG. 2. (a) Ids-Vds curves in linear and logarithmic coordinates. (b) Comparison of the rectification ratio including WTe
2
/MoS
2
,WTe
2
/MoTe
2
,MoS
2
/GaAs, PtSe
2
/GaAs, WS
2
/GaAs.
(c) Ids-Vds curves with photovoltaic behaviors at different wavelengths. (d) The time-resolved photo-response curves under different wavelengthsatzerobias.
Applied Physics Letters ARTICLE scitation.org/journal/apl
Appl. Phys. Lett. 121, 103502 (2022); doi: 10.1063/5.0109020 121, 103502-3
Published under an exclusive license by AIP Publishing
Furthermore, we selected 808nm wavelength for detailed photo-
voltaic analysis. Figure 3(a) shows the I
ds
–V
ds
curves of the photode-
tector with varied light power densities (P) ranging from 0.02 to
19.5 mW/cm
2
. Remarkably, I
sc
monotonously increases gradually
from 0.12 to 100 nA with the increment of P. This phenomenon is
related to the increased separation of photo generated electron–hole
pairs driven by the built-in electric field across the depletion region.
Intuitively, the time-resolved photoresponse behavior under 808 nm
light with varying P is shown in Fig. 3(b). The dark current at zero
bias is as low as 20pA. When the optical signal changes from weak to
strong state, the photo-switching curve between on and off states
shows good reproducibility and photosensitivity. The device can
switch rapidly and reversely between low and high resistance states
and has steep ascending and descending edges, indicating that elec-
tron–hole pairs can be efficiently generated, separated, and recom-
bined across the heterojunction. When the P reaches to 19.5 mW/cm
2
,
the I
light
/I
dark
ratio reaches to 2.86 10
3
. While the P is as weak as
15 lW/cm
2
,theI
light
/I
dark
is calculated to be 80 [Fig. S5(a)], indicating
the excellent weak infrared-light detection ability of the photodetector.
Figure S5(b) suggests that the maximum output electrical power (P
EL
)
of 18.89 nW is generated at 180mV, and the maximum PCE is as large
as 3.52%. Figure 3(c) shows that both the I
sc
and V
oc
increase as the
light power density increases. Particularly, the maximum I
sc
and V
oc
are 100 nA and 0.29 V, respectively. With the help of t he power law fit-
ting formula, I/Pa,wherearepresents the fitting index and is calcu-
lated to be 0.95, which is close to the ideal value of 1, indicating that it
has few intrinsic defects along the interface. Almost all electron–hole
pairs can contribute to photocurrent generation rather than Auger
recombination. This linear relationship between the photocurrent and
the Pclarifies the fact that the measured electrical signals are domi-
nated by the photo generated charge carriers of the device along the
vertical channel rather than the thermionic or tunneling current.
31
As
FIG. 3. (a) Ids-Vds curves of the WTe
2
/GaAs heterojunction under varied light power densities under 808 nm and in dark. (b) Time-resolved photoresponse curves of the
device under varied light power densities at zero bias under 808 nm. (c) Logarithmic plot of Isc and Voc versus light power intensity under 808 nm. (d) R and D
as a function
of light power density at zero bias under 808 nm. (e) The corresponding rise and fall time under 808 nm. (f) The long-term photo-response curves at zero bias under 808nm.
Applied Physics Letters ARTICLE scitation.org/journal/apl
Appl. Phys. Lett. 121, 103502 (2022); doi: 10.1063/5.0109020 121, 103502-4
Published under an exclusive license by AIP Publishing
an important parameter to evaluate the level of the photoelectric
device, Rreflects the sensitivity to incident light, and D
reflects the
ability of the device to detect weak light signals, which are, respectively,
described in the following formulas:
32,33
R¼Iph=Pin ;(4)
D¼R
ffiffiffiffiffiffiffiffiffi
2qJd
p;(5)
where I
ph
is the net photocurrent, P
in
is the incident light power den-
sity, and qis the unit charge (1.610
19
C). J
d
is the dark current
density of the photodetector. As shown in Fig. 3(d),thevalueofR
slightly decreases from 298 to 186mA/W with the increase in P.
When the Pis low, R-value reaches its maximum due to the low
recombination rate of photo-excited carriers with few filled trap states.
With the increase in P, the non-radiative recombination effect
increases, and Rdecreases slightly with full filled trap states and the
increased recombination rate. The maximum R-value can be compara-
ble to other 2D/3D GaAs photodetectors under near-infrared light.
25,27
D
also shows a similar tendency toward R.When0.02mW/cm
2
,the
maximum D
is 1.70 10
12
Jones, which is due to the ultra-low dark
current of 20 pA caused by the large UBnear the interface. Generally,
the rise time (s
rise
) is regarded as the time when the photocurrent rises
from 10% to 90%, while the decay time (s
decay
) is the photocurrent
decrease from 90% to 10%. Figure 3(e) shows the rise time and decay
time at the frequency of 500 Hz according to the photo response
behavior in Fig. S6. The s
rise
and s
decay
are extracted to be 540 and
520 ls, respectively. The fast response speed indicates that the photo-
generated carriers can be separated quickly and drifted to the opposite
electrode because of the strong built-in electric field of 260meV and
less defects at the interface.
25,34
It is obvious from Fig. 3(f) that
260 cycles of repeated testing under weak 808 laser pulses produced
smooth and repeatable photocurrent, suggesting the high stability and
reliability of the Schottky diode.
To further investigate the broadband spectrum of WTe
2
/GaAs
heterojunction, Fig. 4(a) shows the normalized photocurrent in the
range from 400 to 1100 nm. Obviously, the cutoff wavelength of the
heavily n-GaAs is around 900 nm with the optimal wavelength of
600 nm at V
ds
¼0.6 V,
27
while our fabricated WTe
2
/GaAs heterojunc-
tion can respond from 400 to 1100 nm range without external bias,
showing a maximum photocurrent near 900 nm. This unique response
spectrum is owing to the zero-bandgap structure, high light absorption
efficiency of 52nm 1T0-WTe
2
, strong interlayer coupling effect,
and effective built-in electric field across the WTe
2
/GaAs interface.
Figure 4(b) shows that the R of the WTe
2
/GaAs device decreases as a
function of P under various wavelengths, and the maximum R values
for 405, 635, 808, and 1064 nm are 76, 170, 298, and 271 mA/W,
respectively. Figure 4(c) shows the photo generated carriers’ transport
process across the vertical channel in the device, enabling an effective
generation and separation of the photo-induced carriers at the hetero-
junction. In depth, the corresponding mechanism is investigated
through the energy band diagram. According to the previous reports
and the KPFM calculation results,
26
the band alignment of GaAs and
WTe
2
before contact can be obtained from Fig. S7. The WGaAs and
WWTe2arecalculatedtobe4.38and4.64eV,respectively.InFig. 4(d),
after contact, electrons at a higher E
F
value of n-GaAs diffuse to WSM
FIG. 4. (a) Normalized photocurrent broadband spectrum of WTe
2
/GaAs heterojunction and bare GaAs from 400–1100 nm. (b) R values under different wavelengths at zero
bias. (c) 3D Schematic diagram of carriers’ generation and separation under illumination. (d) Energy band diagram of WTe
2
/GaAs heterojunction after contact under visible and
infrared light irradiation.
Applied Physics Letters ARTICLE scitation.org/journal/apl
Appl. Phys. Lett. 121, 103502 (2022); doi: 10.1063/5.0109020 121, 103502-5
Published under an exclusive license by AIP Publishing
WTe
2
side, leaving a positively charged hole in the depletion region of
n-GaAs.Asaresult,energylevelsnearthesurfaceofGaAswillbend
upward. Ultimately, the Fermi-levels of WTe
2
and GaAs are arranged
at the same energy level with a large UBof 570 meV, resulting in a
wide depletion region at the GaAs side. Meanwhile, an effective lateral
built-in electric field of 260 meV pointing from GaAs to WTe
2
side
enables the fast separation of photo-induced carriers. When the pho-
ton energy is higher than the bandgap of GaAs, electron–hole pairs are
generated in the WTe
2
, GaAs, and depletion region and then separated
by a built-in electric field, and photogenerated holes can be easily
transported to the opposite side, eventually forming a negative photo-
current and positive photo-voltage in circuit. However, the photo-
generated electrons must overcome the UBof 0.57 eV at the junction.
While the photon energy (such as 1064nm) is smaller than the optical
bandgap of GaAs, a few photo generated carriers can be only separated
in the gapless WTe
2
side and go across the depletion region along the
vertical channel at several hundred micrometers. Thus, our fabricated
device can respond to a wide spectrum range from 400 to 1100 nm. We
found a negative photo response with 11 nm WTe
2
under 1064 nm in
Fig. S8. In this condition, the energy band on the surface of thin WTe
2
opens when 1064 nm is illuminated, so the suppression to the photocur-
rent in the WTe
2
/GaAs can exceed the response of GaAs. Meanwhile,
as the bandgap opens, a small energy barrier forms at Au/WTe
2
inter-
face, prohibiting carrier transmission.
16,35
Table I summarizes the com-
parison of key figure-of-merit parameters. Some parameters are as
excellent as other reported photodetectors, suggesting the great potential
in fast response near infrared photodetector.
In summary, a high-performance Schottky diode based on a 2D
WSM WTe
2
/GaAs mixed-dimensional heterojunction was demon-
strated. As a result, it delivers a high rectification ratio over 10
3
and
can respond to the wavelength range of 400–1100 nm due to the
zero-bandgap of WTe
2
and the strong built-in electric field across the
heterojunction. When the thickness of WTe
2
is about 52 nm, it dem-
onstrated a maximum Rof 298 mA/W, a D
of 1.7 10
12
Jones, and a
fast response speed of 520/540 ls under 808 nm at zero bias.
Moreover, the maximum I
light
/I
dark
ratio and the PCE are over 10
3
and
3.52%, respectively. Interestingly, when the thickness of WTe
2
is about
11 nm, the negative photoresponse behavior presents under 1064 nm.
All these results indicate that a thickness-dependent WSM WTe
2
/
GaAs heterojunction can extend to other 2D WSM/3D mixed-
dimensional Schottky heterojunctions and have great potential in low-
power consumption and self-driven broadband photodetectors.
See the supplementary material for the details about the fabrica-
tion, characterization, and measurement of the WTe
2
/GaAs mixed
dimensional heterojunction; schematic illustration of the fabrication
process; optical image of WTe
2
/GaAs heterojunction; electrical mea-
surement of bare GaAs and WTe
2
; calculation of the Schottky barrier
height; I
light
/I
dark
ratio and output electric power as a function of P;
time-resolved curve un der 500 Hz; band alignment between WTe
2
and GaAs before contact; and optoelectrical measurement of the heter-
ojunction with 11 nm W Te
2
.
This work was funded by the National Natural Science Foundation
of China (Nos. 62004071, 11904108, and 62175040), the Science and
Technology Program of Guangzhou (No. 202103030001), the China
Postdoctoral Science Foundation (No. 2020M672680), and the “The
Pearl River Talent Recruitment Program” (No. 2019ZT08X639).
AUTHOR DECLARATIONS
Conflict of Interest
The authors have no conflicts to disclose.
Author Contributions
Jina Wang and Hanyu Wang contributed equally to this work.
Jina Wang: Data curation (lead); Formal analysis (equal); Investigation
(equal); Methodology (equal); Writing – original draft (lead); Writing –
review & editing (lead). Hanyu Wang: Data curation (equal);
Investigation (supporting); Writing – original draft (equal); Writing –
review & editing (equal). Quan Chen: Data curation (supporting);
Resources (supporting); Software (supporting). Ligan Qi: Data curation
(supporting); Formal analysis (supporting). Zhaoqiang Zheng: Data
curation (supporting); Project administration (supporting); Supervision
(supporting); Visualization (supporting). Nengjie Huo: Data curation
(supporting); Formal analysis (supporting); Funding acquisition (sup-
porting); Project administration (supporting); Supervision (equal);
Writing – review & editing (supporting). Wei Gao: Conceptualization
(lead); Data curation (lead); Formal analysis (lead); Funding acquisition
(lead); Investigation (equal); Project administration (lead); Supervision
(equal); Writing – original draft (equal); Writing – review & editing
(supporting). Xiaozhou Wang: Data curation (supporting);
Investigation (supporting); Software (equal); Supervision (supporting);
Validation (supporting); Visualization (supporting); Writing – original
TABLE I. Comparison of key parameters of 2D heterojunction self-powered photodetectors.
Device structure
Wavelength
(nm)
I
light
/I
dark
ratio
R
(mA/W)
D
(Jones)
s
rise
/s
decay
(ls/ls)
Detection
range Reference
WTe
2
/GaAs 808 2.86 10
3
298 1.70 10
12
520/540 400–1100 This work
WTe
2
/GaAs 1064 2.16 10
3
271 9.18 10
11
/ / This work
Graphene/GaAs 808 / 122 4.3 10
12
500/350 / 34
MoS
2
/GaAs 780 6.3 10
3
35.2 1.96 10
13
3.4/15.6 200–1200 25
MoS
2
/GaAs 635 / 321 3.5 10
13
17/31 300–900 26
PtSe
2
/GaAs 808 3 10
4
262 10
12
5.5/6.5 200–1200 27
WS
2
/GaAs 880 10
7
527 1.03 10
14
21.8/49.6 200–1000 36
WTe
2
/MoS
2
1050 / 180 2.5 10
8
//35
Applied Physics Letters ARTICLE scitation.org/journal/apl
Appl. Phys. Lett. 121, 103502 (2022); doi: 10.1063/5.0109020 121, 103502-6
Published under an exclusive license by AIP Publishing
draft (supporting). Jingbo Li: Investigation (supporting); Project
administration (supporting); Supervision (supporting); Writing –
review & editing (supporting).
DATA AVAILABILITY
The data that support the findings of this study are available
within the article and its supplementary material.
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Applied Physics Letters ARTICLE scitation.org/journal/apl
Appl. Phys. Lett. 121, 103502 (2022); doi: 10.1063/5.0109020 121, 103502-7
Published under an exclusive license by AIP Publishing
